I am an editor for aircrew computer based training and got this as a supplement to a conventional dictionary, which often does not include aerospace terms, particularly aerospace slang. I've been somewhat disappointed with this volume. It lacks some of the things I expect in a dictionary (such as the part of speech) but does not include enough information to qualify as an encylopedia. Of the ten times I have looked for a specific word in this dictionary, I have only found the word I was looking for twice. Most recently, I was trying to determine if "porpoise" could be used as a verb. Although I found the aerospace definition for "porpoise," the lack of an indication of part of speech made this entry ultimately useless for my purposes. Ultimately, I think that using the web to find aerospace definitions is much easier and more economical than buying this volume.